Grade 8 Music Theory Question

Hello there,


I am new to Baroque music and figured bass, so please excuse my ignorance. I am however not new to music theory- so have decided to take it upon myself to prepare for a grade 8 theory exam. In order to prepare, I have been using Victoria Williams’s excellent grade 8 theory course. I understand most of the content, but have recently run into a problem.

When talking about melodic decoration, Williams says that one must use notes that ‘agree’ with the chord. Using the example of V7 in minor, she says it would be necessary to sharpen the 6th and 7th degrees of the scale , as they ‘fit’ with the chord. Then, moving to minor chord iv, she says it would be best to use the unsharpened 6th and 7th degrees, as this is also what ‘fits’ the chord.

At first, I thought I understood this. As this segment was talking about the melodic minor scale, I checked the mode correlating to V chord in melodic minor, which is mixolydian flat 6, and found that it does indeed include the sharpened 6th and 7th degrees. As chord IV in melodic minor is Major, I assumed that the minor chord iv in the second example she used was a borrowed chord from natural minor. So, I checked the notes of the corresponding mode to chord iv in natural minor- Dorian- and again, this seemed to fit, as it uses the natural 6 and 7.

However, I then noticed that the Harmonic Minor scale has a major V chord and minor iv chord- which made me think that the harmony was in fact derived from this scale all along. Indeed, in a later video, Williams talks about the last chord in minor being dim 7- which is only the case in harmonic minor. Moreover , I have recently read that the harmonic minor scale was the main scale used for harmonising in the baroque period- hence its name. As a result, I checked the modes of harmonic minor that correlate to its iv and V, and unfortunately the result did not fit in line with what Williams was saying in the video. Chord V in harmonic minor, which has Phrygian dominant as the corresponding mode, includes the lowered 6th. And Dorian sharp 4, which corresponds with the minor iv in harmonic minor, includes the raised 7th. Obviously Williams is not wrong, but I am simply yet to understand how to work out what notes ‘fit’ a given chord, and what scale to use at any given time to derive the required harmony. Any light shed on this issue will be very gratefully received!

Thanks-


Ed

Hi, i think that the issue is not quite different to that of changing some degree of a scale when you turn from upward movement to downward movement. Basically, i think the reason behind such changes rest upon practicall (counterpoint) reasons: for instance, take a given scale in uoward movement (lets say, the first thetrachord: the case of a minor scale-mode such as the eolic would be VI-VII-I-II-III; that is, a Major second interval, followed by a minor second interval, then again a Major second interval and at last a Major second interval. It could be argued that, counterpoint-wise if you will, that sequence is compatible with the following: III-III-III-III-III; that is: the sequence' interval structure does not disrupt a sort of underlying harmony.based upon the fifth degree (III is the fifth-dominant of VI...). If you then played IV instead of IV#, it could be also argued thay such an underlying harmonic framework (of dominant nature, so to speak) remained broken. One arguable possibility is that IV# is (again, counterpoint wise) compatible with VII (the fifth of III); so in that case the harmony would extend the relation VI-III to the relation III-VII (yet, still of dominant nature). Finally, if you wanted to keep that extension pattern, you could see that by playing IV instead of IV#, the extension collapsed, so to speak. The same type of analysis could be done regarding many other phrases. Greetings

Thank you for your answer!

Ed